Does chocolate cause constipation?

We found no trial showing that it does. The belief is real and widespread: in a German questionnaire of 1,088 people, chocolate was the food most often named as constipating, by 48 to 64 per cent of respondents, though that survey measured what people believed and not how their bowels behaved. The one trial that fed chocolate to constipated adults found the opposite direction. In 31 Japanese women with constipation, 25 g a day of 72 percent dark chocolate for two weeks gave 4.94 bowel movements a week against 3.33 with white chocolate, in a small manufacturer-funded trial scored from self-reported diaries.

Myth. The claim that chocolate constipates rests on what people report believing. No randomized trial we found shows chocolate slowing the bowel, and nobody has tested ordinary milk chocolate on that question at all.

What the trials found

Dark chocolate in constipated women

The 2025 trial randomized 31 Japanese women aged 26 to 49, each with four or fewer bowel movements a week, to 25 g a day of dark or white chocolate for two weeks. Bowel movements rose to 4.94 a week on dark chocolate against 3.33 on white, a difference that only just reached significance. Estimated stool amount was 694.5 g a week against 342.2 g, judged by eye against the size of an egg rather than weighed, which the authors themselves say should be done properly next time. The trial ran in 2015, was published in 2025, and both the chocolate and the funding came from Meiji.

Cocoa husk fiber in children

In a pilot trial of 48 children aged 3 to 10 with long-standing constipation, a cocoa husk fiber supplement for four weeks left 41.7 percent with hard stools against 75.0 percent on placebo. That product is the fiber of the cocoa shell, a supplement and not chocolate, and the main outcome of the trial, colonic transit time across the whole group, did not reach significance.

Cocoa bran in healthy adults

In a crossover trial of 25 healthy adults without constipation, a chocolate-flavored cereal made with cocoa bran raised stool output by 56 g a day against a low-fiber cereal over two weeks. Again this is the bran of the bean, built into a cereal, and it tells you about cocoa fiber rather than about a bar of chocolate.

Unsettled. The answer stays soft because there is so little to stand on. We found no systematic review or meta-analysis of chocolate and constipation, only small trials, two of them on cocoa fiber products. The single trial of chocolate itself was small, short, in one sex, and funded by the company that made the chocolate.

Who should be careful

The caution in this evidence is about sugar-free chocolate, and it points the other way from the myth. Sugar-free bars are often sweetened with maltitol, a sugar alcohol. In a crossover trial of 20 healthy adults aged 18 to 24, 3.5 oz (100 g) of milk chocolate made with 40 g maltitol caused mild rumbling and wind but did not increase laxation, while 30 g maltitol caused no significant symptoms. Those were single doses in young healthy people, and people with irritable bowel syndrome were not studied.

In a controlled trial of 40 volunteers that was not described as randomized, low-energy chocolates with maltitol blends were eaten for six weeks without a significant change in bowel habit, up to 1.6 oz (45.6 g) of sweetener a day. In the cocoa husk trial in 48 children, no significant adverse effects were reported over four weeks, though safety was not what that small pilot was built to measure.

Not for everyone. If you eat sugar-free chocolate in quantity and notice wind or rumbling, the sweetener is the likelier cause than the cocoa. We found no card on pregnancy, medicines or allergy for this question, so this page says nothing about them.

What expert bodies say

The US National Institute of Diabetes and Digestive and Kidney Diseases lists foods with little or no fiber to avoid when constipated: chips, fast food, meat, and prepared or processed foods. Chocolate is not on that list. That is patient guidance without its own analysis, last reviewed in 2018. We found no position from EFSA, NICE or the American College of Gastroenterology on chocolate and constipation.

How we searched

What would change this answer

• A randomized trial of ordinary milk chocolate in people with and without constipation. Nobody has tested the product most people mean when they repeat the claim.
• A larger, independently funded repeat of the dark chocolate trial, with weighed stools and men as well as women.
• A systematic review pooling the cocoa and chocolate trials. None exists yet.

More on the food itself is on the chocolate page.

Sources

1. ev-choc-01 · Randomized controlled trial(s) · randomized investigator-blind parallel trial, white chocolate as control · n = 31
   However, the bowel movement frequency after dark chocolate ingestion (4.94 ± 0.59 times per week) was significantly higher than after white chocolate ingestion (3.33 ± 0.40 times per week; p=0.049; Fig. 2).
   
   Who: constipated Japanese women aged 26-49 with 4 or fewer bowel movements a week, 25 g/day dark (72% cacao) or white chocolate for 2 weeks
   Effect: bowel movements 4.94 vs 3.33 per week after dark vs white chocolate (p=0.049); 2.75 per week before dark chocolate
   Certainty: Small RCT, one sex, 2 weeks, conducted in 2015, published in 2025; chocolate and Meiji funding; self-report diary.
   Bioscience of Microbiota, Food and Health, 2025, 44(3) (Ingestion of dark chocolate improves constipation and alters the intestinal microbiota in Japanese women) · checked 2026-10-07 · we read the fulltext
2. ev-choc-02 · Randomized controlled trial(s) · randomized investigator-blind parallel trial, white chocolate as control · n = 31
   Furthermore, the stool amount after dark chocolate ingestion (694.5 ± 137.5 g per week) was significantly higher than after white chocolate ingestion (342.2 ± 50.6 g per week; p=0.027).
   
   Who: constipated Japanese women aged 26-49, 25 g/day dark (72% cacao) or white chocolate for 2 weeks
   Effect: stool amount 694.5 vs 342.2 g per week (p=0.027), estimated visually against egg volume
   Certainty: Stool mass was estimated by eye (comparison with an egg); the authors themselves say it should be weighed.
   Bioscience of Microbiota, Food and Health, 2025, 44(3) (Ingestion of dark chocolate improves constipation and alters the intestinal microbiota in Japanese women) · checked 2026-10-07 · we read the fulltext
3. ev-choc-03 · Randomized controlled trial(s) · randomized double-blind placebo-controlled parallel pilot trial · n = 48
   At the end of the intervention, 41.7% and 75.0% of the patients who received cocoa husk supplementation or placebo, respectively, reported having hard stools.
   
   Who: children aged 3-10 with chronic idiopathic constipation, cocoa husk fiber supplement or placebo plus toilet training for 4 weeks
   Effect: hard stools at end 41.7% vs 75.0%; total colonic transit time trend faster, significant only in children with slow baseline transit (-38.1 h difference)
   Certainty: Pilot; this is dietary fiber from cocoa husk, not chocolate; the primary endpoint (transit) is nonsignificant in the whole group.
   Pediatrics, 2006 · checked 2026-10-07 · we read the abstract
4. ev-choc-04 · Randomized controlled trial(s) · randomized double-blind crossover trial · n = 25
   Mean fecal output was significantly higher for cocoa-bran than for low-fiber cereal (56 +/- 14 g/d; P<.001) and equal to the increase seen in the same subjects with wheat fiber in a previous study.
   
   Who: healthy normolipidemic adults, cocoa bran cereal (25.0 g/d total fiber) vs chocolate-flavored low-fiber cereal (5.6 g/d) for 2 weeks each
   Effect: fecal output +56 g/d (P<.001), similar to wheat bran in the same subjects
   Certainty: Healthy people without constipation; cocoa bran, not chocolate.
   Arch Intern Med, 2000 · checked 2026-10-07 · we read the abstract
5. ev-choc-05 · Observational data · cross-sectional questionnaire survey · n = 1088
   The results of systematic questioning yielded chocolate (48-64% of respondents), bananas (29-48%), and black tea (14-24%) as constipating, while prunes (41-52%), coffee (14-24%), wine (8-30%), beer (14-24%), and smoking (42-70% in those who smoked) were considered stool softeners.
   
   Who: 200 healthy controls, 122 patients with chronic constipation and 766 with IBS with constipation, Germany
   Effect: chocolate perceived as constipating by 48-64%, bananas 29-48%, black tea 14-24%; perception, not measured bowel function
   Certainty: Perception, not a measurement; there is no control of how much chocolate was eaten. This very paper is the source of the common claim.
   European Journal of Gastroenterology and Hepatology, 2005, 17(1):109-112 (Muller-Lissner et al.) · checked 2026-10-07 · we read the abstract
6. ev-choc-06 · Randomized controlled trial(s) · double-blind randomized crossover trial · n = 20
   We have shown that 30 g maltitol in chocolate causes no significant symptomatology in young adults; however, 40 g caused mild borborygmi and flatus but no increased laxation.
   
   Who: healthy volunteers aged 18-24, 100 g chocolate with 40 g sucrose, 30 g maltitol or 40 g maltitol
   Effect: 30 g maltitol: no symptom difference; 40 g: more mild borborygmi (P<0.05) and flatulence (P<0.01); laxation not increased
   Certainty: Single doses, young healthy people; people with PCOS not studied.
   J Nutr, 1998 · checked 2026-10-07 · we read the abstract
7. ev-choc-07 · Observational data · controlled human volunteer trial, not described as randomized · n = 40
   All the test chocolates were well tolerated with no significant change in bowel habit or intestinal symptoms even at a daily dose of 45.6 g of non-digestible carbohydrate sweetener.
   
   Who: volunteers eating test chocolates with 22.8 g maltitol alone or with polydextrose or resistant starch, dose doubled every 2 weeks
   Effect: no significant change in bowel habit or intestinal symptoms up to 45.6 g/day non-digestible sweetener; fecal bifidobacteria increased
   Certainty: No description of randomization; endpoints are microbiota, not constipation.
   Br J Nutr, 2010 · checked 2026-10-07 · we read the abstract
8. ev-choc-08 · Randomized controlled trial(s) · randomized double-blind placebo-controlled parallel pilot trial · n = 48
   No significant adverse effects were reported during the study.
   
   Who: children aged 3-10 with chronic idiopathic constipation, cocoa husk fiber supplement or placebo for 4 weeks
   Effect: no significant adverse effects reported
   Certainty: Small pilot, 4 weeks; safety was not the main endpoint.
   Pediatrics, 2006 · checked 2026-10-07 · we read the abstract
9. ev-choc-09 · Position of an expert body · agency patient guidance · n = —
   To help prevent or relieve constipation, avoid foods with little to no fiber, such as
   
   Who: people with constipation (US patient guidance)
   Effect: foods to avoid: chips, fast food, meat, prepared foods, processed foods; chocolate and cocoa not mentioned
   Certainty: Advice without its own analysis; the page was last reviewed in May 2018.
   NIDDK, Eating, Diet, & Nutrition for Constipation (NIH) · checked 2026-10-07 · we read the section